/* lazyproxy.cpp
 *
 * Example of Proxy Pattern.
 */

#include <iostream>

class Subject {

public:
  virtual void operation() = 0;
};

class RealSubject: public Subject {

public:
  virtual void operation() {
    std::cout << "RealSubject operation\n";
  }
};

class Proxy: public Subject {

public:

  Proxy() : p_real_subject(0) {}

  virtual void operation() {

    std::cout << "Proxy operation\n"; 

    if (!p_real_subject)
      p_real_subject = new RealSubject;

    p_real_subject->operation();
  }

  ~Proxy() {
    if (p_real_subject)
      delete p_real_subject;
  }

private:
  RealSubject* p_real_subject;
};

class Client {

public:
  Client(Subject& subject) : _subject(subject) {}

  virtual void do_something() {
    
    _subject.operation();
  }

private:
  Subject& _subject;
};

int main() {
  Proxy proxy;

  Client client(proxy);

  client.do_something();
}